Reference may be had to a number of patents, which were uncovered in a search for self-leveling seats, for a disclosure of the prior art.
U.s. pat. No. 2,939,512, Pohl, June 7, 1960 PA1 U.s. pat. No. 3,315,934, Taylor, Apr. 25, 1967 PA1 U.s. pat. No. 3,341,165, Taylor, Sept. 12, 1967 PA1 U.s. pat. No. 3,466,089, Stueckle, Sept. 9, 1969 PA1 U.s. pat. No. 3,542,423, Lawrence, Nov. 24, 1970 PA1 U.s. pat. No. 3,583,758, Radford, June 8, 1971 PA1 U.s. pat. No. 3,670,834, Rogers, June 20, 1972